Physico-chemical studies of control (TRL 12-13) and nitrosomethylurea-transformed (NMU-3) hepatocyte lines include: 1) Morphology - change in cell shape from squamous to cuboidal when grown on microspheres; marked output of fibronectin from TRL 12-13 cells observed by scanning electron microscopy. Both cell lines seem to prefer microspheres to flat surfaces for growth. 2) Lactate dehydrogenase (LDH) and lactic acid production - LDH enzyme stabilized with proteolytic inhibitors responds differently to inhibitor-free NADH. Molecular differences are observed by gel electrophoresis and isoelectric focusing; exposure of TRL 12-13 to alkaline phosphatase results in conversion to NMU-3 type LDH, implying phosphorylated sites on control enzyme. Spectrophotometric analysis of internal PH demonstrates a four-fold higher rate of acid production in transformed cells, with 75% of the glucose in the growth medium being converted to lactic acid.